piston to wall measurement

[moper]

Is this correct?
Or is it .0020 - .0025 bore size larger than piston size?

No. The bore size should be .002 to .0025 larger than the piston measurement. The clearance is typically built into the piston. Also pay attention to where the piston is measured... If you measure in the wrong spot you will get erroneous measurements.

 

[bOb shingler]

Yes. However by the time you do that and have good rod bolts installed and have the rods resized, you could have bought a whole new set of rods with good rod bolts and already bushed.

So if want my kb pistons to have full floating pins i would have to have the pin hole in the stock rod bored and use a bushing? Thanks

what I did with my 318 is I went to e-bay and bought a set of 340 full floating rods to avoid that machining cost. you might could find a set of "B" or "RB" rods there.

 

[Darren]

The 383 will be a mild street car. I will be having my wrist pins pressed fit.
Good decision?

 

[375inStroke]

Clearance is total, not per side. I ran KB Hyper recommended clearance, .002" pistons, .026" top ring, .016" second, on a 4.030" piston, and no problems running 36 hour endurance races. Believe me, those really test a motor, full throttle, up and down the gears, for 36 hours, with the only break being for gas and driver change. The set comes with spiral locks for use if the rods are floating. If they are press pins, the piston and pin is the same. One just heats the rods, and slips the pin in, and you don't use the locks.

 

[Challenger340]

Is this correct?
Or is it .0020 - .0025 bore size larger than piston size?

Correct, they are calling for the Bore Diameter, to be .0020" to .0025" larger than the Piston.
That is a "minimum" reccomended clearance for installation.
Additional clearance may be required as per the application... C.R., RPM intended, Etc., etc.

USE A TORQUE PLATE, or you will have problems at THAT .0020"to .0025"minimum sizing.
IMO,
If no Torque Plate is used, add about .0005" for a safety factor, me personally... I would just default to .0030" on a BB 440 Engine anyways even with the T/Plate.

Is this a BB or SB Engine ? Whats the Bore size ?